New Way of Extending Satellite Life Saves Millions

coondoggie writes "A new technique to save aging satellites promises to save millions of dollars by extending the life of communications spacecraft. A process developed by researchers from Purdue University and Lockheed Martin has already saved $60 million for unnamed broadcasters by extending the service life of two communications satellites. In a nutshell the technique works by applying an advanced simulation and a method that equalizes the amount of propellant in satellite fuel tanks so that the satellite consumes all of the fuel before being retired from service. Some aging communications satellites are each equipped with four fuel tanks. If one of the tanks empties before the others, the satellite loses control and should be decommissioned, wasting the remaining fuel in the other tanks."

Re:Wow! What an innovative idea!

[Anonymous Coward]

(I don't know if this should count as funny, flamebait, or insighful.)

None of the above. Your post was just stupid.

This post, however, is insightful as fuck.

It's amazing that this was not done initially

[iamacat]

Who launches a multimillion satellite to space without making sure that it fully uses resources left onboard before retiring? Even if four separate fuel tanks are necessary, they can be just connected by small pipes and fuel can be redistributed with a pump powered by satellite's solar cells. It's not a rocket science!

Spent some time with the IT guys

[techpawn]

It really sounds like they just applied load balancing to the fuel tanks...

Re:Misleading report

[Rolgar]

The article is rather vague, saying that's how much they saved, but then how much revenue the satellites bring in over 6 months. If it's the later, that the income these satellites made, not what they saved. If they bring these down at the start of the 6 months instead of the end, they'd still earn the revenue by having the replacement satellites in place at the earlier date. Anyway, this doesn't really save much, it just allows them to push back the cost of launching the new satellites half a year. I suppose over 30 replacement cycles (15 year life, 6 month extra use, 450 years total) barring advancements in satellite engineering, they would finally have save the cost of one satellite and lanch. I'm not saying it's not a good thing that they've done this, but the article is pretty poor about the numbers and over states the benefits.

Re:Wow! What an innovative idea!

[Bartab]

You would be correct sir, if we were talking about an environment with gravity.

However, since we are not, your plan would be as likely to empty at least one tank while filling the rest as to equalize the fuel between them.

Re:It's amazing that this was not done initially

[nsayer]

I think it's a trade-off between safety and predictability on one side and efficiency and progress on the other.

This is largely explained by the public attitude of both sides. To wit:

The soviets launched in secret. When they had a success, they shouted it from the rooftops. When they had a failure, they brushed it under the carpet. If Yuri Gagarin had died in his attempt to be the first man in space, I suspect they would have simply not told anybody and tried again the next week. Heck, by FAI [wikipedia.org] rules at the time, his flight shouldn't have counted, since he parachuted away from the spacecraft during reentry rather than land inside it. The soviets didn't actually land inside their spacecraft until Voskhod 1, in October of 1964, by which time NASA's Mercury project had been over for more than a year. They got away with it because.... wait for it.... nobody was watching.

By contrast, NASA performed all of their activities totally in the public eye. As such, every failure was a public embarrassment and the loss of an Astronaut would have been totally unacceptable. The Apollo 1 fire kept NASA out of orbit for a year and a half while they investigated the cause(s) and fixed a bunch of problems.

Re:NSS?!

[Analogy Man]

Thanks for the clarification. These thrusters adjust the orientation of the satellite. It is also for this reason that there are not fuel lines interconnecting these fuel systems. The additional tubing and failure modes would more than cancel any benefit.

The way I interpret what they are doing is more a matter of planning their usage of thrusters so all of the tanks run out at the same time. This is similar to some work I did in manufacturing where you would balance the usage of the various cutters swapped into a CNC machine so that the all the cutters would be on the same maintenance cycle. If one cutter did 80% of the work and needed to be replaced every 2 hours and the others lasted for a week, you would get much less throughput than if you off loaded some of the work of that cutter to other perishable tools.

Re:sigh

[Sockatume]

It's one of those things that's typical of rocket science, I'd say. Look at the Voyager or Pioneer programs, or the Mars rovers. Astronomy gearheads are geniuses at getting extra mileage out of their projects.

Re:Wow! What an innovative idea!

[dgatwood]

Sure, it seemed likely that an idea that's obvious to the morons here has been nonetheless overlooked by decades of aerospace engineers, but this time that doesn't appear to be the case.

You're right. It's not an obvious solution that has been overlooked. It's a terribly overly complex and non-obvious solution to a relatively simple problem---precisely what I'd expect from an industry with multimillion dollar toilets.

The obvious solution would be to just combine the output of all of the tanks and then split it back off to the engines so that it doesn't matter if one tank contains more propellant than another so long as the average pressure is sufficient... or you know, maybe even something ingenious like... oh, I don't know... valves? Either way, the only thing that matters at that point is that you have some propellant in at least one tank. Am I missing something here?

And before you say it, yeah, I know, valves can get stuck in the cold of space. So can the valve that allows ignition. Your point? :-)

Wow. I didn't know I could be that sarcastic.

Re:Wow! What an innovative idea!

[PachmanP]

Assuming you man one fuel and one oxidizer tank not just one tank (boom!), redundancy.
Oh and more redundancy.
And possibly a little backup.

Re:Wow! What an innovative idea!

[enosys]

The obvious solution would be to just combine the output of all of the tanks and then split it back off to the engines

You mean create a single point of failure?

Re:Wow! What an innovative idea!

[datablaster]

Fuel=zero plus or minus 8kg. That pretty much sums up the level of uncertainty. It's easy from the comfort of terra firma, many degrees removed from actual work-day problem-solving about this to assume that there's a fuel gauge at least as accurate as on a car. Such is not the case. Obviously five decades of space technology is not enough time to have all the answers all the time.

Re:Wow! What an innovative idea!

[rts008]

Wish I had mod points for you for bringing me back down to Earth, so to speak. (why yes, that IS a selfish attitude!)

My first thought when I read the summary was along the lines of this:
WTF?!?!? We've been building semi's (18 wheelers) and satellites about the same amount of time- have the rocket scientists not heard of crossover fuel lines? (they connect left and right tanks and allow for equalization of the fuel level), then I thought...Hmmm...Space, the final frontier...Oh wait! Uhmmm atmospheric pressure, constant gravity from a predictable direction, reasonably constant temps and density- in a moderate range....none of this applies! WTF do we do now?

I hereby revoke my armchair Astrophysics and Rocket Scientist privileges for a week.

Mechanical/electrical engineering in space is no trivial thing. Obvious Earth-bound solutions seem to fail frequently when applied to cold vacuum with micro-gravity. It may not always seem to be so difficult from here, but up there it could be a whole new problem.

Hopefully, even their most inaccurate 'fuel gauge' is better than the one in my car...I either have a quarter of a tank (when FULL) or it reads Empty below an actual 3/4 tank, and you have to use the odometer (Oh Sh*t!, was it reset last fuel-up?!?!?) to guesstimate what the real fuel level may be.

Yes, you all can laugh at me for this. My only semi-reasonable defense can be that I just walked in from work 10 minutes ago, after dealing with John Q Public and Josephine Sixpack for the last 10 hours. I mistakenly bit this worm, dunked the bobber, and now am caught...hook, line, and sinker.

My bad, but I'm at least mouse/man enough to admit it!